1. Field of the Invention
The invention relates to new Ames-test-negative chain-extension agents or cross-linking agents for polyurethane resins and epoxide resins.
2. Prior Art
The production of polyurethanes according to the isocyanate poly-addition process is known. For example, compounds having hydrogen atoms capable of reaction, such as, polyesters with terminal OH groups, are reacted with diisocyanate to form a prepolymer (German Patent Application No. 1,240,654), which are then made in a second step to react at an elevated temperature with a chain-extension agent or cross-linking agent, which is customarily an aromatic diamine. The developing reaction mass, which is capable of being poured, can then be hardened in a mold over an extended period of time. In that case, it is a prerequisite that all of the prepolymer and the chain extension agents or cross-linking agents do not react too quickly in order that a proper processing time is guaranteed in the fluid phase. For this purpose, the following slow-acting diamines, o-chlorobenzidine, 2,5-dichloro-1,4-phenylene-diamines and especially 3,3'-dichloro-4,4'-diaminodiphenyl methane (MOCA), have proven to be useful.
The production of epoxide resins likewise takes place in a known manner. For example, one can proceed in such a way that an active hydrogen compound, such as, alcohols, phenols or acids, is added to a monoepoxy compound while forming chlorohydrine derivatives, which are then converted to glycidyl compounds under HCl-separation. The latter form the basis for the further conversion into epoxide resins using hardeners, such as, anhydrides, diamines or polyamines (Ullmanns Encyclopedia of Technical Chemistry, 4th Edition, Vol. 10, pp 563 et seq.). The diamines, especially methylene dianiline (MDA) and 3,3'-dichloro-4-4'-diaminodiphenylmethane (MOCA), have been shown to be especially useful for this purpose.
The carcinogeneous and mutagenous characteristics of the hitherto known diamines, which are chain-extension agents or cross-linking agents, are considerable disadvantages. Above all, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and methylene dianiline (MDA), have been used on a not very willingly basis because of their suspected carcinogeneous [i.e., Ames-test-positive, see AMES ET AL., PROC. NAT. ACAD. SCI, USA, VOL. 70, 1973, No. 3, pages 782 ff, and No. 8, pages 2281 ff]--their use has even been prohibited in some countries.
A further negative factor is the fact that by the selection of the chain-extension agent or cross-linking agent, the pot time of the elastomer is fixed and can not be varied within a wide range depending upon the use of the elastomer.